The present disclosure relates to an image forming apparatus that transfers a toner image of a plurality of colors onto a moving transfer target, more specifically, relates to an image forming apparatus capable of correcting a color slippage that occurs in the toner image of a plurality of colors that have been transferred onto the transfer target.
An electrographic image forming apparatus is provided with a plurality of image forming units that form toner images of different colors. The image forming units each form a toner image on the surface of the photosensitive drum using an image-developing device, and transfers the toner image onto an endless transfer belt which is the transfer target. The plurality of image forming units sequentially transfer the toner images onto the transfer belt, thereby a color image, in which each of the toner images is superimposed, is formed on the transfer belt. The color image transferred onto the transfer belt is secondarily transferred onto the printing paper by a secondary transfer mechanism, and is subsequently fixed onto the printing paper by being subjected to pressure by a fuser roller which has been heated to 200° C. or higher in the fuser device.
In this type of image forming apparatus, when a temperature of an interior of the image forming apparatus changes, each of the members provided in the image forming apparatus expands and contracts. Such expansion and contraction causes inconsistencies in the movement speed of the transfer belt. These inconsistencies in the movement speed cause a difference between the movement amount of the transfer belt and the movement amount of the photosensitive drum. As a result, when the toner images on the photosensitive drum are sequentially transferred onto the transfer belt, the transfer timing of each of the toner images shifts, causing color slippage. Such color slippage is possible to correct using a well-known color slippage adjustment method. In the color slippage adjustment method, the temperature of the interior of the image forming apparatus is detected using a temperature sensor, and color slippage adjustment is performed at a timing determined on the basis of the temperature change amount.